WPF contextmenu绑定

Question

似乎不能将我的contextmenu中的menuitem绑定到我的viewmodel中的命令。我知道contextmenu并不生活在视觉树中。出于测试目的，我已经在按钮中绑定了相同的命令两次。第一个绑定工作，但我可以在contextmenu中绑定第二个绑定。我可以看到输出中的绑定错误。有人有任何想法？

<HierarchicalDataTemplate DataType="{x:Type inf:OSiteEquipment}" ItemsSource="{Binding Path=SubSystems, Converter={StaticResource subsystemConverter}}" > 
       <Button HorizontalContentAlignment="Left" 
         Command="{Binding DataContext.CommandOpenSelected, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}" 
         CommandParameter="{Binding}"> 

        <TextBlock Text="{Binding Path=PartData.Name}" TextTrimming="CharacterEllipsis" /> 
        <Button.ContextMenu> 
         <ContextMenu>                   

    <MenuItem Header="Add Category" Command="{Binding Path=Parent.PlacementTarget.Tag.CommandOpenSelected, RelativeSource={RelativeSource AncestorType=ContextMenu}}" /> 
         </ContextMenu> 

        </Button.ContextMenu> 
       </Button> 
      </HierarchicalDataTemplate> 

Answer 1

只是删除了“家长”在数据绑定路径：

<HierarchicalDataTemplate DataType="{x:Type inf:OSiteEquipment}" ItemsSource="{Binding Path=SubSystems, Converter={StaticResource subsystemConverter}}" > 
    <Button HorizontalContentAlignment="Left" 
      Command="{Binding DataContext.CommandOpenSelected, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}" 
      CommandParameter="{Binding}"> 

     <TextBlock Text="{Binding Path=PartData.Name}" TextTrimming="CharacterEllipsis" /> 
     <Button.ContextMenu> 
      <ContextMenu> 
       <MenuItem Header="Add Category" Command="{Binding Path=PlacementTarget.Command, RelativeSource={RelativeSource AncestorType=ContextMenu}}" /> 
      </ContextMenu> 
     </Button.ContextMenu> 
    </Button> 
</HierarchicalDataTemplate> 

Answer 2

1. 你已经通过相对源找到Parent - >省略了Parent路径
2. 你没有甚至在PlacementTarget上设置Tag（Button） - >分别设置